Incidence of the Beet Leafhopper-Transmitted Virescence Agent Phytoplasma in local Populations of the Beet Leafhopper, Circulifer tenellus, in Washington State

Phytoplasma diseases are increasingly becoming important in vegetable crops in the Pacific Northwest. Recently, growers in the Columbia Basin and Yakima Valley experienced serious outbreaks of potato purple top disease that caused significant yield loss and a reduction in tuber processing quality. It was determined that the beet leafhopper-transmitted virescence agent (BLTVA) phytoplasma was the causal agent of the disease in the area and that this pathogen was transmitted by the beet leafhopper, Circulifer tenellus Baker (Hemiptera: Cicadellidae). To provide the most effective management of phytoplasmas, timing of insecticide applications targeted against insects vectoring these pathogens should be correlated with both insect abundance and infectivity. Beet leafhoppers were collected from a potato field and nearby weeds in Washington throughout the 2005, 2006, and 2007 growing seasons and tested for BLTVA by PCR to determine the incidence of this phytoplasma in the insects. In addition, overwintering beet leafhoppers were collected throughout Columbia Basin and Yakima Valley and tested for BLTVA to investigate if these insects might constitute a source of inoculum for this phytoplasma from one season to the next. Results showed that 29.6% of overwintering leafhoppers collected near potato fields carried the phytoplasma. BLTVA-infected leafhoppers were also found in both potatoes and nearby weedy habitats throughout the growing season. PCR testing indicated that a large proportion of beet leafhoppers invading potatoes were infected with the phytoplasma, with an average of 20.8, 34.8, and 9.2% in 2005, 2006, and 2007, respectively. Similarly, BLTVA infection rate in leafhoppers collected from weeds in the vicinity of potatoes averaged 28.3, 24.5, and 5.6% in 2005, 2006, and 2007, respectively. Information from this study will help develop action thresholds for beet leafhopper control to reduce incidence of purple top disease in potatoes

Genome-Wide Association Studies in Atherosclerosis

Cardiovascular disease remains the major cause of worldwide morbidity and mortality. Its pathophysiology is complex and multifactorial. Because the phenotype of cardiovascular disease often shows a marked heritable pattern, it is likely that genetic factors play an important role. In recent years, large genome-wide association studies have been conducted to decipher the molecular mechanisms underlying this heritable and prevalent phenotype. The emphasis of this review is on the recently identified 17 susceptibility loci for coronary artery disease. Implications of their discovery for biology and clinical medicine are discussed. A description of the landscape of human genetics in the near future in the context of next-generation sequence technologies is provided at the conclusion of this review